The present invention relates to a method of protecting a radiocommunications terminal from unauthorized use and to a terminal including means for implementing the method.
Without implying any limitation on the invention, xe2x80x9cradiocommunications terminalxe2x80x9d means Personal Handy-Phone System (PHS) cordless telephones, Digital European Cordless Telecommunications (DECT) cordless telephones, Global System for Mobile Communications (GSM) cellular mobile telephones, Cordless Telephony System (CTS) cellular mobile telephones, and pagers.
The invention applies to terminals intended to send and receive a plurality of types of user information and a plurality of types of terminal information.
User information means any information transmitted at the initiative of or to the benefit of the user, for example voice call data, SMS (Short Message Service) messages, calls to emergency services.
By analogy, terminal information means any information transmitted at the initiative of or to the benefit of the terminal, for example location signals or the power of the current cell and of adjoining cells.
Standard radiocommunications terminals include means to protect them against unauthorized use when they are not in operation. A xe2x80x9cPIN codexe2x80x9d known only to the authorized user has to be entered before the terminal can operate. These protection means relate to users"" SIM cards, rather than the terminals as such.
However, prior art terminals do not include any means to protect them against unauthorized use when they are operational. Thus users who have entered their PIN code to activate their terminal, but are not using it at the time, cannot prevent another person using the terminal even though the other person may not be authorized to use it and does not know the PIN code.
The invention therefore aims to alleviate the above-mentioned drawbacks.
In a first aspect, the invention therefore provides a method of protecting a radiocommunications terminal against unauthorized use, the terminal being adapted to send and receive a plurality of types of user information and a plurality of types of terminal information.
According to the invention, when no user information is being transmitted, the terminal is automatically switched to a secure mode in which the sending of at least one type of user information is prohibited and the sending of at least one type of terminal information is authorized, secure mode being canceled by entering a predetermined code. Also, all types of user information may be prohibited in the secure mode.
The type of user information whose transmission is prohibited corresponds primarily to call data. The types of terminal information whose reception is authorized correspond primarily to incoming calls or signaling data. Thus in secure mode the terminal can receive calls and its location within the network can be determined, but it cannot be used to make a call by a user who does not know the predetermined code.
In an embodiment of the invention, the screen of the terminal is deactivated when it is in secure mode. This feature reduces the power consumption of the terminal. The larger the screen, the greater the reduction in power consumption. This embodiment is therefore of particular benefit in the case of terminals with a large graphics screen.
In another embodiment of the invention, and allowing for standardization constraints, sending user information of the emergency services call type is authorized in secure mode.
In a second aspect, the invention proposes a radiocommunications terminal adapted to send and receive a plurality of types of user information and a plurality of types of terminal information.
According to the invention the terminal includes protection means for protecting it against unauthorized use by implementing the above-defined method, the protection means comprising:
switch means for switching the terminal automatically to a secure mode in which the sending of at least one type of user information is prohibited and the sending of at least one type of terminal information is authorized, and
cancellation means for canceling secure mode.